Planet Minis

70Builder · 11-11-2009, 10:01 PM

Can you take a stock CRF50 head (EC-3 HMGK4) and use it in place of an ATC70 head ( HM-D3...there is also a circled L on this head)? The valve size is similar, and I have run a regular Honda head after doing an 88cc cylinder kit on a CRF50. The EC-6 is probably a better option, but I wont strip the 50s that I have already built up. Also, anyone with extra ATC70s that will ship to Canada, I need two more and will pay more than the going rate!

Bucktorious · 11-15-2009, 04:04 PM

an ATC 70 has a domed piston so a 50 head will not work. If you need a new one, try this

NEW_HEAD_ASSY (OLD_70_DOME) (TAKES_EARLY_CAM) CL70_CT70 SL70_XL70 1969_TO_1981 ALL_ATC70&TRX70 22MM/25MM/VALVES (O/S_W/VALVES)

its is NOT oem, but it's close

11-11-2009, 10:01 PM	#1 (permalink)
70Builder PM Newbie Join Date: Nov 2009 Location: Grande Prairie, Alberta, Canada Posts: 8	Head switch? Can you take a stock CRF50 head (EC-3 HMGK4) and use it in place of an ATC70 head ( HM-D3...there is also a circled L on this head)? The valve size is similar, and I have run a regular Honda head after doing an 88cc cylinder kit on a CRF50. The EC-6 is probably a better option, but I wont strip the 50s that I have already built up. Also, anyone with extra ATC70s that will ship to Canada, I need two more and will pay more than the going rate!

11-15-2009, 04:04 PM	#2 (permalink)
Bucktorious PM Newbie Join Date: Apr 2008 Location: Central Minnesota Posts: 82	Re: Head switch? an ATC 70 has a domed piston so a 50 head will not work. If you need a new one, try this NEW_HEAD_ASSY (OLD_70_DOME) (TAKES_EARLY_CAM) CL70_CT70 SL70_XL70 1969_TO_1981 ALL_ATC70&TRX70 22MM/25MM/VALVES (O/S_W/VALVES) its is NOT oem, but it's close

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